Traditionally, battery capacity allocation in mobile electronic devices (e.g., PDAs, cellular telephones, laptop computers, . . . ) could be implemented by preserving a predetermined portion of the maximum battery capacity. Preserving a set portion of the battery capacity could provide sufficient power to the device in a low-power state to retain data for a reasonable time in volatile memories related to the mobile electronic device such that the device could be connected to an alternative power supply. For example, a PDA can switch to a low-power state (e.g., the device appears to turn off to the end user) when the battery reaches 50% of the total battery capacity. This can preserve data in the PDAs volatile memory for a period of time, for example 72-hours, such that there is sufficient time to recharge the PDA or switch batteries in the PDA.
Generally, information can be stored and maintained in one or more of a number of types of storage devices, such as memory devices. Memory devices can be subdivided into volatile and non-volatile types. Volatile memory devices generally lose their information if they lose power and typically require periodic refresh cycles to maintain their information. Volatile memory devices include, for example, random access memory (RAM), dynamic RAM (DRAM), static RAM (SRAM), and the like. Non-volatile memory devices can maintain their information whether or not power is maintained to the memory devices. Non-volatile memory devices include, but are not limited to, flash memory, read only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), non-volatile RAM, and the like.
Therefore, traditional battery capacity allocation results in, for example, only 50% of the battery capacity being available to the end user of the device for normal mode operations (e.g., making cell phone calls, checking stock prices on a PDA, . . . ). This can be true even where the end user readily has an alternative power supply available (e.g., a second battery, among others). Thus, current battery capacity allocation can create inefficiencies in battery use.
For example, where a user has a second battery available for a PDA, where the first battery drops to 50% capacity, the user must switch batteries to continue to work on the device (e.g., at 50% the device goes into low power mode to preserve volatile memory data). This is true even though the user does not need, for example, 72 hours to switch the batteries. Thus, the user can lose up to 50% of available battery capacity. Where a user could alternatively allow the battery to drop to, for example, 0.1% of capacity before switching batteries, the 0.1% capacity could retain volatile memory data for the several minutes the user might need to switch batteries. This can result in use of, for example, 99.9% of the battery capacity as compared to 50% of the battery capacity under conventional battery allocation.
Recently, some mobile device operating systems (e.g., Microsoft™ Windows Mobile 5.0™ OS, among others) have implemented support for persistent storage technologies. Persistent storage employs some nonvolatile device memory (e.g., flash memory) to prevent the loss of data when the battery is completely drained. Where an operating system supports persistent memory, the battery capacity can be allowed to run to a much lower portion of overall battery capacity because there is both less power consumption (e.g., lower power consumption requires less battery capacity to maintain data for a 72 hour period) and less fear that when battery capacity reaches 0% that there will be large data losses (e.g., where all data is stored in nonvolatile memory, a loss of all power does not result in memory loss). Systems and methods that can interact with operating systems that support persistent storage can further improve battery capacity by allowing a battery to run to 0% capacity where there will be no loss of data as a result of employing nonvolatile memory in the device.
The use of portable computer and electronic devices has greatly increased demand for high capacity batteries. Digital cameras, digital audio players, personal digital assistants, and the like, generally seek to employ high capacity batteries (e.g., evolution from alkaline to Li Ion batteries, among others). By better managing battery capacity allocation, more capacity can be efficiently used without increasing the size of a battery or, alternatively, a smaller sized efficiently allocated battery can supply similar capacity to larger conventionally allocated batteries. It is desirable to create systems and methods for facilitating improved battery capacity allocation.